
local test = "can_you?__15__50"
function string:split1(sep)
  sep = sep or ","
  local result = {}
  local i = 1
  for c in (self..sep):gmatch("(.-)"..sep) do
      result[i] = c
      i = i + 1
  end
  return result
end
for _, i in ipairs(test:split1("__")) do
  print(i)
end